CHAPTER III. 



THE DENTAL TISSUES. 



IT is usual to speak of there being two kinds of teeth, 

 namely, horny or albuminous, and calcined teeth ; but of the 

 development of the former nothing is accurately known, and 

 it is hence impossible to determine in what relation they 

 really stand to other, or calcined, teeth. 



These latter are composed of one or more structures, 

 which are in great measure peculiar to the teeth (although, 

 what is to all intents and purposes dentine, is to be found 

 in the skeletons and in the dermal appendages of some fish, 

 and other exceptions might be found to the absolute accu- 

 racy of the statement), and hence are called " dental tissues." 

 Notwithstanding the existence of certain transitional forms, 

 it is not possible to doubt the propriety of a general division 

 of dental tissues into three, viz., Dentine, Enamel, and 

 Cementum. 



The first named of these constitutes the greater part of 

 all teeth, and so far predominates in mass over the other 

 constituents that, in very many cases, the tooth would 

 retain its form and character after the removal of the enamel 

 and cementum. 



This central body of dentine, enclosing the pulp, is very 

 often covered by a cap of enamel, which forms the surface 

 of the tooth ; this may be very partial, as in the eel or the 

 newt, in which animal only this enamel-capped tip of the 

 tooth projects far above the surface of the mucous membrane ; 

 or it may cover a much larger proportion of the tooth, as 



